1. Field of the Invention
The present invention relates to a method of manufacturing a substrate to be used for a liquid ejection head such as an inkjet recording head adapted to eject ink toward a recording medium and form an image on the surface of the recording medium.
2. Description of the Related Art
Inkjet recording heads of the type adapted to eject ink from an ejection port formed above an ink ejection pressure energy generating element are conventionally known as liquid ejection head. A technique of forming an ejection energy generating element on the front surface of a substrate and supplying ink to an ejection port from the rear surface of the substrate has been adopted for inkjet recording heads of this type.
Japanese Patent Application Laid-Open Publication No. 2009-61665 discloses a method of manufacturing an inkjet recording head substrate of the above identified type by forming blind holes of two different types by means of a laser and subsequently forming an ink supply port by means of anisotropic etching. Japanese Patent Application Laid-Open Publication No. H09-123468 discloses a method of forming a positioning reference mark for machining by irradiating light to and thereby discoloring a resin layer (photoresist layer).
A method of using a positioning reference mark is conceivable for forming an ink supply port at a predetermined position by means of the manufacturing method described in Japanese Patent Application Laid-Open Publication No. 2009-61665. Then, blind holes of two different types can be formed highly accurately. However, when a positioning reference mark is formed by the method disclosed in Japanese Patent Application Laid-Open Publication No. H09-123468, light is irradiated onto a resin layer to reduce the optical transmittance of the resin layer and thereby discolor the resin layer. Therefore, when a silicon substrate has an inorganic material layer (inorganic layer) of Si, SiO, SiO2, or Poly-Si, a resin layer needs to be formed on the inorganic material layer before applying the method of Japanese Patent Application Laid-Open Publication No. H09-123468. Then, a large number of steps are required to form a positioning reference mark.